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Closeup portrait of a Bolivian red howler monkey (Alouatta sara) sitting in treetops with big balls hanging in the Pampas del Yacuma, Bolivia Stock Photo - Alamy
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Amazing Facts on X: "The loudness of a monkey is actually relative to the size of its testicles. Researchers found out that the smaller the testicles, the louder the monkey 📣 https://t.co/irBAZEzyRc" /
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